300-410 IPv4 Access Control Lists Practice Question
This 300-410 practice question tests your understanding of ipv4 access control lists. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A network engineer runs the following command to troubleshoot an IPv4 Access Control Lists issue:
R1# show access-lists 120
Extended IP access list 120
10 permit tcp 192.168.1.0 0.0.0.255 any eq 80
20 permit tcp 192.168.2.0 0.0.0.255 any eq 443
30 deny ip any any log
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The ACL permits HTTP traffic from 192.168.1.0/24 and HTTPS traffic from 192.168.2.0/24, and denies all other traffic with logging.
The output shows an extended ACL with two permit statements: the first permits TCP traffic from 192.168.1.0/24 to any destination on port 80 (HTTP), and the second permits TCP traffic from 192.168.2.0/24 to any destination on port 443 (HTTPS). The final deny ip any any log statement explicitly denies all other IP traffic and logs matches, which is standard practice for ACL troubleshooting. Therefore, option A correctly describes the ACL's behavior.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The ACL permits HTTP traffic from 192.168.1.0/24 and HTTPS traffic from 192.168.2.0/24, and denies all other traffic with logging.
Common exam trap: answer the scenario, not the keyword
Cisco often tests the ability to read ACL output precisely, and the trap here is that candidates may overlook the specific port restrictions (eq 80 and eq 443) and assume the ACL permits all traffic from the source networks, or misinterpret the 'log' keyword as affecting the permit/deny action.
Detailed technical explanation
How to think about this question
Extended ACLs are processed top-down; the first matching permit or deny is executed, and an implicit deny ip any any exists at the end even if not explicitly configured. The 'log' keyword on the deny statement causes a log message to be generated for each packet that matches that line, which is useful for monitoring denied traffic but can impact CPU if traffic is high. In real-world scenarios, such ACLs are often applied on interfaces facing the internet to restrict outbound web traffic from specific subnets.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
IPv4 Access Control Lists — This question tests IPv4 Access Control Lists — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The ACL permits HTTP traffic from 192.168.1.0/24 and HTTPS traffic from 192.168.2.0/24, and denies all other traffic with logging. — The output shows an extended ACL with two permit statements: the first permits TCP traffic from 192.168.1.0/24 to any destination on port 80 (HTTP), and the second permits TCP traffic from 192.168.2.0/24 to any destination on port 443 (HTTPS). The final deny ip any any log statement explicitly denies all other IP traffic and logs matches, which is standard practice for ACL troubleshooting. Therefore, option A correctly describes the ACL's behavior.
What should I do if I get this 300-410 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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